You can use TextColumn’s ValueConverter to configure how the value is displayed in the column. In this scenario, when you use filtering, you should also use the TextColumn’s EditorValueConverter and its ConvertBack method to convert the value back to DateTimeOffset.

Additionally if you use DateTime you can also use a TemplateColumn. You can display the Date value as a string (inside a TexBlock for example) on each row and use the DatePicker in the filter to filter a Date. You can find a sample of this functionality.